1. Field of the Invention
The invention relates to systems for treating waste produced at residential or commercial sites, or on transport vehicles/vessels (e.g., on board rail cars or marine vessels).
2. Discussion of Background
Our earlier patents/applications disclose waste treatment systems in which an incoming waste liquid is initially separated into primarily solid and primarily liquid components, and the solid and liquid components are then further treated. Such treatment systems are disclosed in our prior U.S. Pat. Nos. 5,447,630; 5,725,762; and 5,843,304, which are incorporated herein by reference. These systems can be utilized, for example, for household waste, where sewage systems are unavailable or overly burdened, or in low lying areas where septic systems are also unfeasible. These systems are also advantageous in that they are capable of providing resulting effluents which are more environmentally satisfactory as compared with conventional treatment systems. Systems as disclosed in our earlier patents/applications can also be utilized in commercial or apartment complexes, on board marine vessels and other transport vehicles (such as rail systems), or with portable toilet facilities.
The present invention provides improvements to certain components, and overall system improvements (for at least certain applications), to the systems disclosed in our above-mentioned earlier patents/applications which are incorporated herein by reference. It is therefore an object of the invention to provide an improved waste treatment system which can be used at various locations for treating waste at the site, or close to the site, at which the waste is created.
It is a further object of the invention to provide a waste treatment system which is compact so that it can be readily used at various locations or on various vehicles or vessels, with the entire or substantially the entire system housed as a unit.
It is another object of the invention to provide an improved filtration system which can be utilized as a component of a waste treatment system. The filtration system can be housed as a unit with other components of a treatment system, or the filtration assembly can be provided as a separate component or a component which is installed in a system designed/assembled for a particular facility.
It is a further object of the invention to provide an improved valve assembly for isolating an incineration assembly from portions of the treatment system which are upstream of the incineration assembly.
The above and other objects and advantages are achieved in accordance with the present invention. In accordance with a presently preferred embodiment which can be utilized, for example, as a household treatment system, the waste is initially separated by a separator, which separates the waste stream into a primarily liquid component and a primarily solid component. The primarily solid component is fed to an incineration device, while the primarily liquid component is fed to a filter assembly. For certain applications, such as a household, or a small marine vessel, the system is preferably housed as a unit, with the unit including the separator, the incineration assembly, and the filter assembly. For larger applications, the components can be assembled in various configurations. For example, for a large marine passenger or military vessel, plural filter assemblies can be associated with a single separator, so that the various filters accommodate larger amounts of liquid. After filtration of the liquids, additional treatment, e.g., ultraviolet treatment, can optionally be provided, in large or small systems. In addition, solids from the separator can be sent to a solids collection vessel which periodically doses the solids to an incineration device, or the solids from the separator can be forwarded to plural incineration assemblies.
The separator is as disclosed in our earlier patents/applications, and is advantageous in a number of respects. For example, the separator requires no input energy, yet provides a high degree of separation between liquids and solids, so that first and second output components are provided, one of which is primarily liquid, and the other of which is primarily solid waste. The separator is also advantageous in that it can operate continuously (even during a power outage) and can handle large flow volumes, with the waste separated as it flows continuously through the separator. Thus, for most if not all applications, upstream holding chambers (i.e., upstream from the separator) can be avoided. In other words, waste flows are preferably directly sent to the separator from their source, without an intermediate holding tank. The inventors have recognized upstream holding chambers/tanks as undesirable in that the solids can dissolve or emulsify, making downstream separation and treatment more difficult or less effective. Since the separator handles a significant volume of waste in a relatively short period of time as the waste flows through the separator, the downstream components will generally be the limiting factor with respect to the amount of time required to treat the solid and liquid components of the waste. Therefore, in larger systems, a single separator (or, for very large systems, a small number of separators) can be used in conjunction with plural or multiple downstream filter and/or incineration assemblies.
In accordance with one aspect of the invention, an improved filter assembly is provided. Our earlier systems utilized, for example, a pair of side-by-side filter assemblies, so that when one of the assemblies is being cleaned (e.g., by subjecting the filter elements to microwave energy), the liquid flow could be directed to the other filter assembly. With the present invention, an xe2x80x9cup-downxe2x80x9d filter assembly is provided, in which a pair of filter elements is disposed in the same filter assembly. The direction of liquid flow through the assembly is periodically changed so that in a first mode of operation the liquid is filtered through one of the filter elements, while in a second mode of operation the liquid passes through a second filter element. Preferably, during this second mode of operation, the first filter element is being purged or back flushed.
The filter elements are also cleaned utilizing microwave energy. However, with the arrangement of the present invention, the cleaning operation utilizing microwave energy is required much less frequently, thus allowing for longer periods of operation between cleaning cycles and reducing the amount of energy required for cleaning. In particular, the alternating (xe2x80x9cup-downxe2x80x9d) flow assembly moves the debris or particles which can accumulate upon a filter, to reduce clogging, so that a greater amount of liquid can be handled by the filter assembly between cleaning cycles (i.e., cleaning with microwave energy). In a preferred form of the invention, the filter assembly also includes one or more improved filter elements. In particular, the filter element is a dual density or multiple density filter element in which the liquid flow initially passes through the more dense filter portion (i.e., having smaller pores, or in other words, a higher pore density), and the liquid then passes through the less dense filter element (having larger pores, or in other words, a lower pore density). This filter element is less susceptible to particles becoming clogged deeply within the filter element (i.e., at locations which are difficult to clean), since the liquid is first exposed to the finer portion of the filter element. The coarser or less dense portion of the filter element provides support for the finer (higher pore density) portion of the filter element, and also provides for improved air flow, for example, when an incineration cleaning operation is being performed on the filter element. The less dense portion of the filter element is also advantageous in that liquids are more easily drained from the filter element since liquids are less susceptible to retention by capillary action of the larger pores/passages extending through the less dense filter portion.
Although various system components and system assemblies are shown, it is to be understood that various components could be utilized separately and/or can be substituted with other components. For example, the improved filter assembly could be replaced with other types of filter assemblies, for example, assemblies described in our earlier patents/applications. However, the filter assembly as disclosed herein is presently preferred. It is also to be understood that various components could be utilized separately if desired in a given system, for example, if a waste stream is such that a filtration system is not required, or if a waste stream is such that the filtration assembly is the only treatment component required. Further, components such as the solids incinerator and/or the filter assembly can be advantageously utilized with various types of separators, with the separator selected based upon the waste stream being treated (for example, a cyclonic or other type of separator or a dewatering device may be desirable where there has been some break-down or maceration of the solids such as when the waste stream is from a vacuum toilet). Of course, the quantity and arrangement of the components (e.g., number of filter assemblies, number of solids incinerators, number of separators, etc.) could also vary depending upon the facility to which the waste treatment system is to be applied as will be apparent from the description herein.